diff --git a/aleksis/apps/chronos/models.py b/aleksis/apps/chronos/models.py
index 3ed7596645a7ec299fca1ede9cd7897d3045280a..23c61ebda671fe1c1bd0cb2bbfb80b0d6afc65b4 100644
--- a/aleksis/apps/chronos/models.py
+++ b/aleksis/apps/chronos/models.py
@@ -1261,6 +1261,10 @@ class AutomaticPlan(LiveDocument):
                 )
             update = False
             for version in versions:
+                if not version.object:
+                    # Object exists no longer, so we can skip this
+                    continue
+
                 # Check if the changed object is relevant for the time period of the PDF file
                 if isinstance(version.object, Event):
                     date_start = version.object.date_start